Monday, 15 June 2020

Quiz 3 - Memory Management in OS with Answers

Quiz 3 - Memory Management in OS

(Answers are in bold blue)

1. What is a reallocation register?
(a) A base register used to give the limit value for a process.
(b) A base register used to give the start physical address for a process.
(c) A base register used to give the page offset of a page table for a process.

2. What is swapping?
(a) Copying a process from one memory location to another memory location to allow space for other processes
(b) Copying process from disk to me mory to provide page-in service
(c) Copying process from/to memory to/from disk to allow space for other processes

3. Consider basic memory management with segments, where segment is either a process or a hole between two processes. Which of the memory allocation methods performs the poorest with respect to wasted memory space? (Note: consider the memory space utilization as the performance metric when evaluating which method performs poorest)
(a) First-fit
(b) Best-fit
(c) Next-fit

4. Why is there a reference bit?
(a) to reference that a page was read
(b) to reference that a page was modified
(c ) to reference that a page was accessed

5. Consider a paging system with the page table (un-optimized, i.e., not multi-level and not inverted) stored in memory. If a memory reference takes 200 nanoseconds, how long does a paged memory reference take?
(a) 200 nanoseconds,
(b) 300 nanoseconds,
(c) 400 nanoseconds,
(d) none of the above

6. Consider a logical address space of eight pages (2^3) of 1024 bytes (2^10) each, mapped onto a physical memory of 32 frames (2^5). How many bits are there in the logical address?
(a) 13 bits
(b) 15 bits
(c) 8 bits

7. Which of the following tells the system whether or not a pager (memory manager) needs to write a page to the disk when it is replaced?
(a) Base register
(b) Dirty bit
(c) Page table
(d) Limit register

8. Pick a statement that is FALSE about TLB (Translation Lookaside Buffers)
(a) It is used to save performance
(b) Associative registers may be used to implement it
(c) It eliminates page faults
(d) It relies on the locality of reference principle

9. The idea of overlays is to keep an entire program in memory so that all data can be accessed quickly
(a) True
(b) False

10. Compaction may be used to eliminate external fragmentation
(a) True
(b) False


*Thanks to Klara Nahrstedt, University of Illinois

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